SwapPool

Swap pool contract. May or may not be covered by a backstop pool. Conceptionally, there are two ways to temporarily disable a pool: The owner can either pause the pool, disabling deposits, swaps & backstop, or the owner can set the pool cap to zero which only prevents deposits. The former is for security incidents, the latter for phasing out a pool.

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SwapFees

struct SwapFees {
  uint32 lpFee;
  uint32 backstopFee;
  uint32 protocolFee;
}

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totalLiabilities

uint256 totalLiabilities

The liabilities of the pool Cannot just use totalSupply() as the totalLiabilities will accumulate also the LP fees from swaps. This is fixed point number using the decimals of this pool

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reserve

uint256 reserve

The amount of pool tokens usable for swaps This is fixed point number using the decimals of this pool

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reserveWithSlippage

uint256 reserveWithSlippage

The amount of pool tokens plus the slippage The relationship with reserve is: reserveWithSlippage = slippageCurve.psi(reserve, totalLiabilities) However this relationship will never hold precisely and will deviate slightly for numerical reasons!! All code needs to work even if this relationship does not hold This is fixed point number using the decimals of this pool

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maxCoverageRatioForSwapIn

uint256 maxCoverageRatioForSwapIn

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safeRedeemPercentage

uint256 safeRedeemPercentage

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safeRedeemInterval

uint256 safeRedeemInterval

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lastBackstopBurnTimestamp

uint256 lastBackstopBurnTimestamp

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lastAvailableAmountForSafeRedeem

uint256 lastAvailableAmountForSafeRedeem

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protocolTreasury

address protocolTreasury

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lastDepositAt

mapping(address => uint256) lastDepositAt

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lastDepositAmount

mapping(address => uint256) lastDepositAmount

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backstop

contract IBackstopPool backstop

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router

contract IRouter router

router instance for this swap pool

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slippageCurve

contract ISlippageCurve slippageCurve

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deposit

function deposit(uint256 _depositAmount, uint256 _minLPAmountOut, uint256 _deadline) external returns (uint256 sharesToMint_, int256 fee_)

Deposits amount of tokens into pool Will change cov ratio of pool, will increase delta to 0

Parameters

Name	Type	Description
_depositAmount	uint256	The amount to be deposited, an amount of pool tokens
_minLPAmountOut	uint256	Minimum amount of pool lp tokens to mint
_deadline	uint256	Unix timestamp after which the transaction will revert

Return Values

Name	Type	Description
sharesToMint_	uint256	Total number of pool lp tokens minted
fee_	int256	The slippage reward (a negative fee), fixed point number using the pool decimals

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quoteDeposit

function quoteDeposit(uint256 _depositAmount) external view returns (uint256 sharesToMint_, uint256 slippageReward_)

Get a quote for the effective amount of tokens for a deposit

Parameters

Name	Type	Description
_depositAmount	uint256	The amount to be deposited

Return Values

Name	Type	Description
sharesToMint_	uint256	Total number of pool LP tokens to be minted (incl. slippage)
slippageReward_	uint256	The reward due to slippage, fixed point number using the pool decimals

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withdraw

function withdraw(uint256 _sharesToBurn, uint256 _minimumAmount, uint256 _deadline) external returns (uint256 payoutAmount_, int256 fee_)

Withdraws liquidity amount of asset ensuring minimum amount required

Parameters

Name	Type	Description
_sharesToBurn	uint256	The liquidity to be withdrawn, an amount of LP tokens
_minimumAmount	uint256	The minimum amount of returned pool tokens that will be accepted by user
_deadline	uint256	Unix timestamp after which the transaction will revert

Return Values

Name	Type	Description
payoutAmount_	uint256	Amount of pool tokens withdrawn after applying withdrawal fee
fee_	int256	The penalty due to slippage (a positive fee), fixed point number using the pool decimals

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quoteWithdraw

function quoteWithdraw(uint256 _sharesToBurn) external view returns (uint256 payoutAmount_, uint256 slippagePenalty_)

Get a quote for the effective amount of tokens for a withdrawal

Parameters

Name	Type	Description
_sharesToBurn	uint256	Total number of pool LP tokens to be burned

Return Values

Name	Type	Description
payoutAmount_	uint256	The amount to be withdrawn (incl. slippage)
slippagePenalty_	uint256	The penalty due to slippage

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backstopBurn

function backstopBurn(address _owner, uint256 _sharesToBurn) external returns (uint256 amount_)

Burns swap pool LP tokens of owner, will get compensated using backstop liquidity (reedem swap pool shares) Can only be invoked by backstop pool, disabled when pool is paused

Parameters

Name	Type	Description
_owner	address	The LP's address whose LP tokens should be burned
_sharesToBurn	uint256	The number of LP tokens of this pool to burn

Return Values

Name	Type	Description
amount_	uint256	The amount of asset() tokens that the burned shares were worth

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getMaxRedeemSwapPoolShares

function getMaxRedeemSwapPoolShares() external view returns (uint256 maxShares_)

Get the maximum amount of swap pool LP tokens that can be burned (CR <= 100%)

Return Values

Name	Type	Description
maxShares_	uint256	The maximum amount of LP tokens that can be burned

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backstopDrain

function backstopDrain(uint256 _amount, address _recipient) external returns (uint256 swapAmount_)

For backstop pool to withdraw liquidity if swap pool's coverage ratio > 100% Can only be invoked by backstop pool

Parameters

Name	Type	Description
_amount	uint256	The amount of asset() tokens to be moved out of swap pool
_recipient	address	Address to send the funds to

Return Values

Name	Type	Description
swapAmount_	uint256	The amount of asset() tokens that are transfered to _recipient

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quoteBackstopDrain

function quoteBackstopDrain(uint256 _amount) external view returns (uint256 swapAmount_)

Get a quote for the effective amount of tokens for a backstop drain

Parameters

Name	Type	Description
_amount	uint256	The amount of tokens to be withdrawn for backstop liquidity

Return Values

Name	Type	Description
swapAmount_	uint256	The amount to be withdrawn (incl. slippage)

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quoteSwapInto

function quoteSwapInto(uint256 _amount) public view returns (uint256 effectiveAmount_)

Get a quote for the effective amount of tokens for a swap into

Parameters

Name	Type	Description
_amount	uint256	The amount of pool tokens to swap into the pool

Return Values

Name	Type	Description
effectiveAmount_	uint256	Effective amount, incl. slippage (penalty or rewards)

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quoteSwapOut

function quoteSwapOut(uint256 _amount) public view returns (uint256 effectiveAmount_, uint256 protocolFeeWithSlippage_, uint256 effectiveLpFee_, uint256 backstopFee_)

Get a quote for the effective amount of tokens, incl. slippage and fees

Parameters

Name	Type	Description
_amount	uint256	The amount of pool asset to swap out of the pool

Return Values

Name	Type	Description
effectiveAmount_	uint256	Effective amount, incl. slippage and fees
protocolFeeWithSlippage_	uint256	The protocol fee that is to be sent to the treasury
effectiveLpFee_	uint256	The actual LP fee – totalLiabilities should be incremented by this value
backstopFee_	uint256	The effective backstop fee

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coverage

function coverage() external view returns (uint256 reserves_, uint256 liabilities_)

returns pool coverage ratio

Return Values

Name	Type	Description
reserves_	uint256	Current amount of usable asset() tokens (without slippage)
liabilities_	uint256	total amount of asset deposited by liquidity providers

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getExcessLiquidity

function getExcessLiquidity() external view returns (int256 excessLiquidity_)

Computes the excess liquidity that forms that valuation of the backstop pool is defined as b + C - B - L where

• b is reserve

• C is the amount of asset() tokens in the pool

• B is reserveWithSlippage

• L is totalLiabilities The excess liquidity is a fixed point number using the decimals of this pool

Return Values

Name	Type	Description
excessLiquidity_	int256	The total excess liquidity of this pool, can be negative

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sharesTargetWorth

function sharesTargetWorth(uint256 _sharesToBurn) public view returns (uint256 amount_)

Returns the worth of an amount of pool shares (LP tokens) in underlying principle

Parameters

Name	Type	Description
_sharesToBurn	uint256	The number of LP tokens to burn

Return Values

Name	Type	Description
amount_	uint256	The amount of asset() tokens that the shares are worth

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swapFees

function swapFees() public view returns (uint256 lpFee_, uint256 backstopFee_, uint256 protocolFee_)

Return the configured swap fees for this pool

Return Values

Name	Type	Description
lpFee_	uint256	Fee that benefits the pool's LPers, in 0.0001% (e.g. 300 -> 0.0300%)
backstopFee_	uint256	Fee that benefits the backstop pool, in 0.0001% (e.g. 150 -> 0.0150%)
protocolFee_	uint256	Fee that benefits the protocol, in 0.0001% (e.g. 50 -> 0.0050%)

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depositingUnfreezesAt

function depositingUnfreezesAt() public view returns (uint256 depositingUnfreezesAt_)